DNA–inorganic hybrid material as selective absorbent for harmful compounds

DNA functionalized programmable hybrid biomaterials for targeted multiplexed applications

With the advent of DNA nanotechnology, DNA-based biomaterials have emerged as a unique class of materials at the center of various biological advances. Owing to DNA's high modification capacity via programmable Watson-Crick base-pairing, DNA structures of desired design with increased complexity have been developed. However, the limited scalability, along with poor mechanical properties, high synthesis costs, and poor stability, reduced the adaptability of DNA-based materials to complex biological applications. DNA-based hybrid biomaterials were designed to overcome these limitations by conjugating DNA with functional materials. Today, DNA-based hybrid materials have attracted significant attention in biological engineering with broad application prospects in biomedicine, clinical diagnosis, and nanodevices. Here, we summarize the recent advances in DNA-based hybrid materials with an in-depth understanding of general molecular design principles, functionalities, and applications. Finally, the challenges and prospects associated with DNA-based hybrid materials are discussed at the end of this review.

Selective Accumulation of Rare-Earth and Heavy Metal Ions by a Fucoidan-Inorganic Composite Material

The accumulation of rare-earth and heavy metal ions from wastewater is important for industrial technology. However, practical accumulators of metal ions are expensive with respect procurement of raw materials, synthesis, and preparation. Therefore, it is preferable to accumulate metal ions using sustainable resources, such as natural polymers. Fucoidan, a water-soluble natural polymer, is a sulfated polysaccharide from the cell-wall of brown algae. Therefore, fucoidan behaves as an acidic polysaccharide in an aqueous solution. We prepared a fucoidan-inorganic composite material by mixing fucoidan and a silane coupling reagent, bis(3-(trimethoxysilyl)propyl)amine (SiNSi). This fucoidan-SiNSi (F-SiNSi) composite material showed a water-insoluble property. This is due to the encapsulation of fucoidan into a three-dimensional network of SiNSi with siloxane bonding. When the F-SiNSi composite material is immersed in a metal ion-containing aqueous solution, the composite material accumulated the metal ions. The binding affinity of each metal ion was Ca(II), Mg(II) << Nd(III) < Cu(II), Zn(II), Ni(II), La(III) < In(III) < Y(III). Additionally, the maximum-accumulated amounts of the Nd(III), Cu(II), Zn(II), Ni(II), La(III), In(III), and Y(III) ions were 140, 200, 190, 200, 200, 230, and 270 nmol per mg of fucoidan, respectively. Furthermore, the molar ratios of the acidic groups (the sulfate and carboxyl groups) in the fucoidan and accumulated metal ions, were 0.081–0.156. Therefore, the F-SiNSi composite material showed a selectivity for rare-earth and heavy metal ions. The accumulation mechanism of the rare-earth and heavy metal ions was related to the carboxyl groups in the fucoidan.

Preparation of bioplastic consisting of salmon milt DNA

The microplastic that pollutes the ocean is a serious problem around the world. The bioplastic consisting of biopolymers which is degraded in nature, is one of the strategies to solve this problem. Although the bioplastics consisting of protein, polysaccharide, polylactic acid, etc., have been reported, which consist of DNA, one of the most important materials in the genetic process, have not been reported to the best of our knowledge. In addition, a large amount of DNA-containing materials, such as salmon milts, is discarded as industrial waste around the world. Therefore, we demonstrated the preparation of a bioplastic consisting of salmon milt DNA. The DNA plastic was prepared by the immersion of a DNA pellet in a formaldehyde (HCHO) solution and heating. As a result, the water-stable DNA plastics were obtained at the HCHO concentration of 20% or more. Particularly, the DNA plastic with a 25% HCHO treatment showed water-insoluble, thermally stable, and highly mechanical properties. These are due to the formation of a three-dimensional network via the crosslinking reaction between the DNA chains. In addition, since DNA in plastic possesses the double-stranded structure, these plastics effectively accumulated the DNA intercalator, such as ethidium bromide. Furthermore, the DNA plastics indicated a biodegradable property in a nuclease-containing aqueous solution and the biodegradable stability was able to be controlled by the HCHO concentration. Therefore, salmon milt DNA has shown the potential to be a biodegradable plastic.

Preparation of Gellan Gum-Inorganic Composite Film and Its Metal Ion Accumulation Property

Gellan gum is one of the water-soluble anionic polysaccharides produced by the bacteria Sphingomonas elodea. In this study, we prepared gellan gum-inorganic composite films by mixing the gellan gum and a silane coupling reagent—3-glycidoxypropyltrimethoxysilane (GPTMS). These gellan gum-GPTMS composite films were stable in an aqueous solution and showed a thermal stability. In addition, these composite films indicated a mechanical strength by the formation of the three-dimensional network of siloxane. We demonstrated the accumulation of metal ions from a metal ion-containing aqueous solution by the composite film. As a result, although the composite film indicated the accumulation of heavy and rare-earth metal ions, the light metal ions, such as Mg(II) and Al(III) ions, did not interact with the composite material. Therefore, the accumulative mechanism of metal ions using a composite film was evaluated by IR measurements. As a consequence, although the accumulation of heavy and rare-earth metal ions occurred at both the −COO− group and the −OH group in the gellan gum, the accumulation of light metal ions occurred only at the −OH group.

Versatile synthesis of a highly porous DNA/CNT hydrogel for the adsorption of the carcinogen PAH

Herein, a novel pathway to prepare a porous structured DNA hybrid hydrogel has been described, using a transiently existing Pickering emulsion that is continuously generated during the reaction. The as-prepared highly porous gel features significantly improved capability for trace amounts of PAH removal.